Some timepiece mechanisms, notably but not restricted to chronograph mechanisms, comprise mobile elements associated with cams, in particular heart-pieces, which cooperate with the pane of a hammer to achieve a return to a given position (return to zero), and/or holding in said particular position. These hammers are often made to be flexible, or in several articulated parts, or the mechanism requires a positioning spring.
EP Patent 275746 in the name of MONTRES BREGUET S A discloses a device for pivoting an arbor of a timepiece movement wherein a pivot passes through a jewel fixed in a setting, and an endstone comprising a bearing surface receiving the end of the pivot, and, in the stop position of the pivot on the endstone, the normal to the tangent plane common to the pivot and to the bearing surface is oblique with respect to the axis at an angle of cant, and defines with the axis an endstone plane oriented at a yaw angle with respect to a reference of a plate of the movement. This device includes means for adjusting the yaw angle and/or the angle of cant in order to regulate and adjust the rate of the movement.